Drupal is an open source content management platform. Equipped with a powerful blend of features, Drupal supports a variety of websites ranging from personal weblogs to large community-driven websites.

Documentation: Drupal has a very strong documentation which includes lot of tutorials for newcomers and full API description.

Frequency of releases: The major releases of Drupal is rather seldom and coming out in one or two years.The minor and bugfix releases is coming out every two or three months.

Client-side integration: Drupal includes integrated jQuery library.

Community: Drupal community is large and active. You can ask you question on the Drupal forums or go thematical IRC channel to get live support.